The speed of a man along with the river is 20km/h and speed of the man against the river current is 10km/h. calculate the speed of the man in still water and speed of the river.

Explanation

To solve the problem, we need to establish the relationship between the speed of the man in still water, the speed of the river current, and the speeds given in the problem.

1. **Define Variables**:
- Let \( v_m \) be the speed of the man in still water (in km/h).
- Let \( v_r \) be the speed of the river current (in km/h).

2. **Set Up Equations**:
- When the man is moving downstream (with the current), his effective speed is the sum of his speed in still water and the speed of the river:
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